Thanksgiving Dinner 2011: Why Diets Fail

Here's just what you want to hear on the eve of the holiday season: Nutritionists at Cornell University have made a strong argument that when it comes to overeating, free will is a myth.

Their research indicates that the reason diets fail is that they address the wrong problem. It's not possible simply to reduce caloric intake by willpower. The environmental cues that cause us to overeat are so powerful that when it comes to eating, free will is overwhelmed.

So here's what must be done: Change those deadly cues, not condemn ourselves for lack of willpower. This according to David Levitsky, professor of nutritional sciences at Cornell, and his graduate student, Carly Pacanowski.

"It is this myth -- that we are free to choose what we eat -- that is the foundation of the obesity epidemic," the researchers argue in a study that is to be published in the journal Public Health Nutrition.

The authors analyzed hundreds of articles on eating behavior, and conducted their own experiments, before reaching this conclusion. For the long term, they lay out steps that anyone can take to curb their caloric intake. But the research also suggests that the holidays ahead are a "perfect storm" for overeating.

Thanksgiving, especially, combines some of the worst environmental cues that they blame for overeating -- lots of food right under our noses, lots of company to share the moment, lots of choices of what to eat, and you can overload your plate because someone else is bound to be eating even more.

But it isn't the food itself that is the culprit. Nearly every year about this time the American Chemical Society puts out a press release showing that the traditional Thanksgiving meal is healthy -- honey-baked turkey and ham may be good for your heart, bread crust used in the stuffing is a "rich source of cancer-fighting antioxidants," cranberries rank number one in antioxidants, canned corn is a disease-fighter, greens are good for the eyes, even pumpkin pie can promote better vision. So what's the worry?

There's way too much of it. Millions of Americans will gain a pound over the holidays, and according to some research, that pound will still be around for next year's Thanksgiving.

When you step on the scales next January, you may feel like a weak glutton who doesn't have the willpower to push back from the table when the belly is full. Forget the guilt, according to the Cornell team. It's more complicated than that.

The researchers cite numerous studies indicating that most of us believe we can -- or at least should -- be in control of our food consumption.

"Apparently, Americans believe their eating behavior is totally controlled by their own will," the study says. "For most Americans, the obesity epidemic is a result of being weak willed, lacking the will-power to make healthy decisions."

They go on to cite studies showing that all diets eventually fail; what's lost will soon be regained. Only surgery, which brings its own problems, has proved effective at eliminating obesity. Surgery takes free will out of the equation, the researchers conclude. Instead, it imposes "physical constraint" on the amount of food that can be eaten at one time.

The researchers lay out a series of "environmental cues" that can be overwhelming. They include:

Serving size. "The amount of food people consume at a meal is determined to a large extent by the amount of food placed on the plate in front of them." A Cornell colleague, Brian Wansank, has shown that even reducing the size of the plate has an impact.

Too much variety. "As the number or colors of M&Ms or jelly beans increases, so does consumption." If there are more items to choose from, people will choose more.